feat(class): 添加班级删除功能

- 在班级列表表格中新增“操作”列，添加删除按钮
- 实现删除班级的接口调用逻辑
- 删除成功后刷新班级列表
- 删除当前选中班级时清空选中状态
- 添加成功和失败的用户提示信息

enlish-vue/src/layouts/components/AddClassDialog.vue

@@ -0,0 +1,86 @@
+<template>
+	<el-dialog v-model="visible" title="新增班级" width="480px" :close-on-click-modal="false">
+		<div class="space-y-4" v-loading="loading">
+			<el-form label-width="80px">
+				<el-form-item label="班级名称">
+					<el-input v-model="name" placeholder="请输入班级名称，如：二班" clearable />
+				</el-form-item>
+				<el-form-item label="年级">
+					<el-select v-model="gradeId" placeholder="请选择年级" style="width: 260px">
+						<el-option v-for="g in gradeOptions" :key="g.id" :label="g.title" :value="g.id" />
+					</el-select>
+				</el-form-item>
+			</el-form>
+		</div>
+		<template #footer>
+			<div class="flex justify-end gap-2">
+				<el-button @click="visible = false">取消</el-button>
+				<el-button type="primary" :disabled="!canSubmit" @click="handleSubmit">确定</el-button>
+			</div>
+		</template>
+	</el-dialog>
+</template>
+
+<script setup>
+import { ref, computed, watch } from 'vue'
+import { getGradeList } from '@/api/grade'
+import { addClass } from '@/api/class'
+
+const props = defineProps({
+	modelValue: { type: Boolean, default: false },
+	defaultGradeId: { type: [Number, String], default: null }
+})
+const emit = defineEmits(['update:modelValue', 'success'])
+
+const visible = computed({
+	get: () => props.modelValue,
+	set: (val) => emit('update:modelValue', val)
+})
+
+const loading = ref(false)
+const name = ref('')
+const gradeId = ref(null)
+const gradeOptions = ref([])
+
+const canSubmit = computed(() => name.value.trim().length > 0 && !!gradeId.value)
+
+async function fetchGrades() {
+	loading.value = true
+	try {
+		const res = await getGradeList(1, 100)
+		const d = res?.data
+		gradeOptions.value = Array.isArray(d?.data) ? d.data : []
+		if (props.defaultGradeId && !gradeId.value) {
+			gradeId.value = Number(props.defaultGradeId)
+		}
+	} finally {
+		loading.value = false
+	}
+}
+
+async function handleSubmit() {
+	if (!canSubmit.value) return
+	loading.value = true
+	try {
+		await addClass(name.value.trim(), Number(gradeId.value))
+		ElMessage.success('新增班级成功')
+		emit('success')
+		visible.value = false
+	} finally {
+		loading.value = false
+	}
+}
+
+watch(
+	() => props.modelValue,
+	(v) => {
+		if (v) {
+			name.value = ''
+			gradeId.value = props.defaultGradeId ? Number(props.defaultGradeId) : null
+			fetchGrades()
+		}
+	}
+)
+</script>
+
+<style scoped></style>